carnival.cpp: In function 'int ask(std::vector<int>)':
carnival.cpp:10:27: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=]
printf("%d ",v.size() );
~~~~~~~~ ^
carnival.cpp: In function 'void process(int, int, int)':
carnival.cpp:32:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if( c == 1 ) for( int i = 0 ; i < v.size() ; i++ ) mark[v[i]] = mark[nu];
~~^~~~~~~~~~
carnival.cpp:33:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if( d == 1 ) for( int i = 0 ; i < v2.size() ; i++ ) mark[v2[i]] = mark[nu];
~~^~~~~~~~~~~
carnival.cpp: In function 'int ask(std::vector<int>)':
carnival.cpp:14:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&ret);
~~~~~^~~~~~~~~~~
carnival.cpp: In function 'int main()':
carnival.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&n);
~~~~~^~~~~~~~~